If one looks objectively at how players drafted in slots 7-10 traditionally perform, one would probably conclude that Ellis was an above average pick. He showed signs of becoming a Pro Bowl level player before his leg injury in his second season and I don't think he ever quite fully recovered his speed after that.
There is little doubt that he outperformed all the other DEs chosen in the first round in that draft.
Here are all the first rounders that went after Ellis:
9 Jacksonville Fred Taylor RB Florida
10 Baltimore Duane Starks CB Miami
11 Philadelphia Tra Thomas T Florida State
12 Atlanta Keith Brooking OLB Georgia Tech
13 Cincinnati Takeo Spikes OLB Auburn
14 Carolina Jason Peter DE Nebraska
15 Seattle Anthony Simmons OLB Clemson
16 Tennessee Kevin Dyson WR Utah
17 Cincinnati Brian Simmons OLB North Carolina
18 New England Robert Edwards RB Georgia
19 Green Bay Vonnie Holliday DT North Carolina
20 Detroit Terry Fair CB Tennessee
21 Minnesota Randy Moss WR Marshall
22 New England Tebucky Jones SS Syracuse
23 Oakland Mo Collins G Florida
24 N.Y. Giants Shaun Williams SS UCLA
25 Jacksonville Donovin Darius SS Syracuse
26 Pittsburgh Alan Faneca G Louisiana State
27 Kansas City Victor Riley T Auburn
28 San Francisco R.W. McQuarters CB Oklahoma State
29 Miami John Avery RB Mississippi
30 Denver Marcus Nash WR Tennessee
A fair number of solid players but the only guy who I think he has been a much better player than Ellis overall is Moss.
A case could be made for Darius who is overrated and a safety, Faneca who is very good but an OG, Taylor who is often injured, Spikes who is good and Brooking who is good.
The real reason this pick irks Cowboys fans is that we were supposed to pick Randy Moss who ended up being an All-Pro WR.